This invention relates to a process for folding an airbag used as an impact protection device in a vehicle. Until it is operated, the airbag is stowed together with an inflating device (normally an air generator) in a tub-shaped housing which is accommodated, for example, in a steering wheel of a vehicle.
Processes for folding the airbag to accommodate it in such housings are known. For example, in the so-called rolling fold, the airbag, which is cut essentially to a round shape, is first folded into an elongated shape with parallel sides and the free ends are then folded back to produce an essentially rectangular package.
Steering wheels used to accommodate such an airbag, on the other hand, generally have a so-called "four-spoke shape"; that is, four spokes extend from an outer steering wheel rim to an impact body with diagonally extending walls. In order to fit an airbag folded by the above described process (which forms a rectangular stowage shape) into such an impact body it has been necessary either to fold the airbag into such a small size that it does not protrude beyond the housing walls of the impact body, or to fold it so that it projects slightly beyond the diagonally extending housing walls of the impact body, and must be stuffed at these points during the mounting of a housing cover.
It is therefore an object of the present invention to provide an airbag, and a process of folding an airbag, which provide a stowage shape adapted to a tub-shaped housing.
This object is achieved by the airbag arrangement according to the invention, in which the airbag is first folded into an elongated shape with parallel sides in the same manner previously described, and then further reduced in size by folding it to form a rectangular shape. Next, it is folded diagonally, forming points, which by further diagonal folding come to be situated adjacent recesses into which they are then fitted from the direction of the previous folding plane. The reduction of the packing measurements by the utilization of such recesses is particularly advantageous and decreases the extension of the airbag out of the housing. Also, in comparison to known embodiments, one less packing layer is created, so that the housing can be more compact, and take up less installation space. It can also be designed with greater freedom as to its shape.
In the airbag arrangement according to the invention, the airbag can be packed into a trapezoidal housing in a simple manner, and disposed with an improved utilization of space and therefore in a very flat fashion.
All embodiments of the invention have in common that the tear seams arranged in the housing cover are less stressed in the stowed condition because the airbag is folded together very uniformly and exerts a uniform pressure on the housing cover.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.